WO2006087802A1

WO2006087802A1 - Tsunami detection system

Info

Publication number: WO2006087802A1
Application number: PCT/JP2005/002601
Authority: WO
Inventors: Yukihiro Terada; Keiji Ito; Takenori Abe; Takashi Fujita
Original assignee: Hitachi Zosen Corporation
Priority date: 2005-02-18
Filing date: 2005-02-18
Publication date: 2006-08-24
Also published as: JPWO2006087802A1; JP4588065B2

Abstract

A tsunami detection system has a horizontal position calculation section (31) for obtaining, based on positioning data obtained by GPS receivers (11, 21), a horizontal relative position relative to the center position of mooring of a floating body (4); a tsunami determination region setting section (33) for setting a tsunami determination region S, which depends on the horizontal relative position of the floating body, for determination of the next time; and a tsunami determination section (32) for determining, based on the horizontal relative position of the floating body and a tsunami determination region set last time, whether the floating body is present in the tsunami determination region.

Description

Specification

Tsunami detection system

Technical field

[0001] The present invention relates to a tsunami detection system capable of measuring a tsunami using radio waves of a plurality of satellite forces.

Background art

[0002] In recent years, GPS (Global Positioning System) has been used for positioning technology, and it has become possible to accurately measure the position of an object regardless of land or sea! .

[0003] By the way, the present inventors have made many proposals on a method for measuring the displacement of the sea surface using GPS, and some of them are related to a system for detecting a tsunami. These documents are shown below.

(1) “Development of GPS Tsunami Meter” (Monthly “Ocean” extra N0.15 1998) (hereinafter referred to as Non-Patent Document 1).

(2) “ReaH: ime observation of tsunami by RTK- (JP!) Earth Planets

Space, 52, 841-845, 2000 (The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS) etc.) (hereinafter referred to as Non-Patent Document 2).

(3) "Development of GPS Tsunami Meter-Practical Experiment on Offshore Ofunato" (The IEICE Transactions Vol.J84-B NO.12 December pp2227-2235) (December 2001) (hereinafter, Non-Patent Document 3 Called).

(4) JP-A-11-63984 (hereinafter referred to as Patent Document 1).

(5) JP 2001-147263 A (hereinafter referred to as Patent Document 2).

(6) JP 2001-281323 A (hereinafter referred to as Patent Document 3).

[0004] Of these documents, Non-Patent Document 1, Non-Patent Document 3, and Patent Document 1 relate to a tsunami detection system using a real-time kinematic method (hereinafter referred to as RTK method). Reference 2 and Patent Document 3 relate to the principle of obtaining positioning accuracy equivalent to that of the RTK method by a method different from the RTK method.

[0005] Then, when detecting a tsunami, the above non-patent document 1 using the RTK method 1 non-patent document 3 According to the configuration described in Patent Document 1, the base station (which is also a reference station) and a measurement floating body are included, and the measurement floating body includes an anchor submerged on the seabed in a predetermined sea area. The floating body is connected to the anchor via a chain or other rope and a weight is attached, and a measuring device is provided on the floating body.

[0006] The base station and the measurement floating body are equipped with a GPS receiver, and the displacement vector with respect to the base line vector of the floating body is calculated by the RTK method, so that the accurate position of the measurement floating body is obtained in real time. It is made to be required!

[0007] In addition, Non-Patent Document 1 and Non-Patent Document 3 disclose a report based on a measurement result in a state where no tsunami has occurred, and Patent Document 1 discloses a process for determining displacement data. A configuration is disclosed that is input to the science department to determine whether the displacement is due to a tsunami.

[0008] Further, except for the above-mentioned documents, the displacement of a floating body installed offshore was measured using the RTK method with a GPS receiver provided on the floating body, and the relative position with respect to the base station was measured. Thereafter, a method for measuring the wave height is obtained by measuring the change in the relative position and obtaining the wave height from the change in the relative position [see, for example, Japanese Patent Laid-Open No. 10-185564 (hereinafter referred to as Patent Document 4). ].

Disclosure of the invention

Problems to be solved by the invention

[0009] By the way, in Patent Document 4 described above, only the detection of wave heights including waves is performed. Also in Patent Document 1, displacement data is input to the judgment processing unit and is caused by a tsunami. Although it is only described that it is determined whether it is a failure or not, the present inventors detect tsunamis by removing short-period components such as waves by frequency discrimination and extracting long-period components including tsunami components. Has succeeded.

[0010] However, until now, as shown in Non-Patent Document 3, experiments have been carried out with a floating body installed in a sea area with a water depth of about 50m. It is small and the sea surface displacement increases as the water depth becomes shallower. If a floating body is installed offshore for early tsunami detection, it is expected that the water depth will become deeper and tsunami detection will be difficult. Therefore, an object of the present invention is to provide a tsunami detection system that does not depend on sea level displacement.

Means for solving the problem

[0012] A tsunami detection system according to the present invention includes a floating body moored on the sea surface by a mooring device, and a position measuring device that is provided on the floating body and can detect its own position by receiving radio waves from a plurality of satellites. A tsunami detection system comprising a tsunami detection device capable of detecting the presence or absence of a tsunami based on horizontal position data obtained by the position measuring device,

In the above tsunami detection device,

A tsunami detection area setting unit that inputs horizontal position data obtained by the position measuring device at predetermined time intervals and sets a tsunami determination area according to the current measurement position of the floating body relative to the mooring center position of the floating body, and this tsunami A tsunami determination unit that determines whether or not there is a tsunami based on whether or not the next measurement position of the floating body is included in the determination region set in the determination region setting unit is provided.

[0013] Further, according to another configuration of the present invention, the tsunami determination area in the tsunami detection system is a movement limit line indicating a movement limit of a predetermined radius centered on the mooring center position of the floating body, and extends radially from the floating body center. A judgment boundary line obtained by connecting each of the intersection points where the plurality of straight lines and the movement limit line intersect each other and a plurality of line segments connecting the floating body center are respectively divided at a predetermined ratio.

The area between

The invention's effect

[0014] According to the above tsunami detection system, the horizontal relative position with respect to the mooring center position of the floating body is obtained by radio waves of satellite power, and the floating body is within the tsunami determination area set according to the horizontal relative position of the floating body. Because the tsunami is detected by determining whether it is present or not, the tsunami is detected even if the depth is deep! It can be detected easily and accurately only by the amount of movement in the horizontal direction. Brief Description of Drawings

FIG. 1 is a perspective view showing a schematic overall configuration of a tsunami detection system according to an embodiment of the present invention. It is.

FIG. 2 is a block diagram showing a schematic configuration of a mobile station in the tsunami detection system.

FIG. 3 is a block diagram showing a schematic configuration of a reference station in the tsunami detection system.

FIG. 4 is a block diagram showing a schematic configuration of a tsunami detection device provided in the reference station.

FIG. 5 is a plan view for explaining a method for setting a tsunami determination area of the tsunami detection device.

FIG. 6 is a plan view for explaining a method for setting a tsunami determination area of the tsunami detection device.

FIG. 7 is a flowchart for explaining a tsunami detection method in the tsunami detection system. BEST MODE FOR CARRYING OUT THE INVENTION

[0016] [Embodiment]

Hereinafter, a tsunami detection system according to an embodiment of the present invention will be described with reference to FIGS.

[0017] The tsunami detection system according to the present embodiment floats a floating body on the sea surface, and based on the horizontal movement amount (including distance and direction) of the floating body on the sea surface (two-dimensional horizontal plane), the presence or absence of a tsunami The horizontal movement of the floating body is measured by the real-time kinematic positioning method, which is a relative positioning using GPS (Global Positioning System).

[0018] In other words, as shown in Fig. 1, this tsunami detection system is fixed on land, has a known three-dimensional absolute position, and receives radio waves from multiple (at least four) GPS satellites 1. Base station 2 to obtain positioning data, and a mooring cord (such as a mooring tool) 3 such as a chain on the sea surface (specifically, the sea area where the tsunami is to be measured) at a predetermined distance from this base station 2. The moored floating body 4 and the mobile station 5 which is provided on the floating body 4 side and receives radio waves from a plurality of GPS satellites 1 as in the reference station 2 and obtains positioning data, and both the stations 2 and 5 A tsunami that inputs the obtained positioning data and determines the presence or absence of a tsunami based on the current horizontal measurement position of the mobile station 5 (horizontal position data, in other words, the measurement position of the floating body center) A detection device (see FIG. 3) 6 is provided. In the present embodiment, the tsunami detection device 6 is described as being provided in the reference station 2.

[0019] As shown in Fig. 2, the mobile station 5 includes a mobile-side GPS receiver (position measuring device) 11 that can receive radio waves from a GPS satellite 1 and detect positioning data, and the mobile side. GPS reception A mobile-side radio device (radio transceiver) 12 capable of transmitting the positioning data obtained by the device 11 by radio is provided.

In addition, as shown in FIG. 3, the reference station 2 receives a radio wave from the GPS satellite 1 and can detect positioning data, and a reference-side GPS receiver (position measuring device) 21 and the mobile-side radio A reference-side wireless device (radio transceiver) 22 that receives the positioning data transmitted by the device 12 is provided, and the tsunami detection device 6 is arranged as described above.

In the tsunami detection device 6, the positioning data obtained by both the GPS receivers 11 and 21 are input directly and directly via the reference-side wireless device 22, and real-time based on the both positioning data. Using the kinematic positioning method (which uses the carrier phase, hereafter referred to as the RTK method), at least the horizontal relative position of the mobile station 5 with respect to the reference station 2, that is, on the sea surface of the center of the floating body 4 (in a two-dimensional horizontal plane) The horizontal position is accurately measured, and the presence or absence of a tsunami is detected based on this measurement position.

[0022] As shown in Fig. 4, the tsunami detection device 6 includes positioning data obtained at both stations 2 and 5, [for example, carrier phase value, distance between satellite and receiver antenna (pseudo distance) , Satellite orbit information, and positioning system used to include time-series data (GPS time), etc., and calculate the relative position of mobile station 5 with respect to reference station 2 using the RTK method In addition, a horizontal position calculation unit 31 for obtaining the current center position of the floating body 4 relative to the mooring center position of the floating body 4 (which is a relative position with respect to the reference station), that is, a horizontal relative position, and a horizontal position obtained by the horizontal position calculation unit 31 Enter the relative position and the tsunami judgment area S defined in the past, determine whether the current center position of the floating body 4 exists (is included) in the tsunami judgment area S, and the floating body 4 is tsunami If it exists in the judgment area S, it is a tsunami. The tsunami judgment unit 32 to be disconnected and the horizontal relative position obtained by the horizontal position calculation unit 31 are input, and the tsunami that sets the tsunami judgment region S for future judgment based on the horizontal relative position and the mooring center position And a determination area setting unit 33.

[0023] Note that the position measurement of the floating body 4 by the GPS receivers 11 and 21 is performed at predetermined time intervals. Therefore, the tsunami determination period in the tsunami determination unit 32 also matches this position measurement period. It has been made.

That is, the above-mentioned “determined in the past” means that the previous position measurement cycle (tsunami determination cycle) This means that it was determined based on the horizontal relative position of the floating body 4 obtained in (5). The tsunami determination area S determined based on the position means that it will be used for tsunami determination in the next position measurement cycle (which is also the tsunami determination cycle).

Here, a method for setting the tsunami determination area S in the tsunami determination area setting unit 33 will be described.

First, the basic concept when setting the tsunami determination area S will be described.

[0027] As described above, the floating body 4 is moored to an anchor (not shown) installed on the seabed via a mooring cable body 3 such as a chain. Thus, according to the length of the mooring cord 3, it can move within a circle with a predetermined radius R on the sea surface. The boundary line indicating the outer edge of the movable range is referred to as a movement limit circle (movement limit line) A. The center position of the floating body 4 on the sea surface of the movement limit circle A is the mooring center position C. Of course, the mooring center position C corresponds to the horizontal position of the anchor on the seabed.

[0028] As described above, the floating body 4 can theoretically move within the movement limit circle A, but in reality, when an external force such as wind or ocean current (force due to meteorological conditions) acts. Means that the floating body 4 moves in that direction and the mooring center position force is also separated, and in this away direction (which is also the direction of external force action), for example, the opposite direction due to the weight of the mooring cord 3 Because of this force, the movable range becomes narrower, but in the opposite direction, the movable range becomes wider because it can move excessively by the distance from the mooring center position. Therefore, this movable range is usually set to a size according to the horizontal position of the floating body 4 in consideration of external forces such as wind and ocean currents that can be assumed, and the floating body is set in a range beyond this movable range. If 4 moves, it can be judged that an excessive energy wave, that is, a tsunami, was applied.

[0029] Based on such an idea, a portion within the movement limit circle A and excluding the movable range that can be moved by an external force that can be normally assumed is defined as a tsunami determination region S. For example, in FIG. 5, when represented by a circle of radius r (hereinafter referred to as a judgment boundary line) B indicating the boundary of the movable range that can be moved by a normal external force, the tsunami judgment area S is the movement limit circle A. And the judgment boundary line B (shown with diagonal lines). [0030] In Fig. 5, the floating body 4 is located at the mooring center position C. However, normally, the floating body 4 is either one of the two due to an external force such as wind or ocean current. The mooring cable 3 is floating at a position where the tension and the external force of the mooring cable body 3 are balanced.

[0031] Hereinafter, a method for setting the tsunami determination region S in such a state will be described with reference to FIG.

[0032] In this case, the tsunami determination area S includes a movement limit circle A having a predetermined radius around the mooring center position C of the floating body 4, a plurality of straight lines L extending radially from the center F of the floating body 4, and the above movement limit. Judgment boundary line B obtained by connecting a plurality of division points M, each of which is obtained by dividing the line segment L connecting each intersection K where the circle A intersects with the floating body center F with a predetermined ratio, into a curved line (may be a straight line) And the range between.

[0033] In other words, it is assumed that the floating body 4 exists on the same horizontal plane as the mooring center position C, and the distance that will move in the next tsunami judgment cycle when a tsunami comes The tsunami determination area S is set using the ratio to the ratio (hereinafter referred to as the area setting coefficient, specifically, a positive value smaller than 1).

In more detail, the tsunami determination area S is determined based on the current position (measurement position) of the floating body 4, that is, based on the horizontal relative position with respect to the mooring center position C, and naturally, in the mooring center position direction. Is easy to move, but difficult to move in the opposite direction, so multiple straight lines L extend radially from the center position F of the floating body 4, and the intersection K of each of these straight lines L and the movement limit circle A and the floating body center F Multiplying the line segment L by the above area setting factor to determine the movable range B of the floating body 4, and the range between the extension of this movable range B and the movement limit circle A (indicated by the diagonal lines) ) Is the tsunami determination area S.

[0035] As shown in FIG. 6, the movable range B is easily moved to the mooring center position C side in the direction in which the floating body 4 is being flown. The range on the far side becomes narrower, and on the opposite side it becomes wider.

[0036] The region setting coefficient is determined in advance by experience, experiment, etc., and the value is constant for the line segment L in all directions of the floating body center F. Depending on the force situation, different values for each line segment L may be used in stages.

[0037] Next, the tsunami detection procedure by the tsunami detection system is based on the flowchart of FIG. I will explain.

[0038] First, the positioning data obtained by the mobile-side GPS receiver 11 of the mobile station 4 provided on the floating body 4 floating on the sea surface is transferred via the mobile-side and reference-side radio devices 12, 22 Then, it is input to the tsunami detection device 6 of the reference station 2, and the positioning data obtained by the reference-side GPS receiver 21 is also input to the tsunami detection device 6.

[0039] Next, in the tsunami detection device 6 described above, positioning data of both stations 2 and 5 is input to the horizontal position calculation unit 31, where the mobile station 5 relative to the reference station 2 is based on the RTK method. The position, that is, the center position F of the floating body 4 with respect to the mooring center position C on the sea surface is obtained every predetermined time (step 1).

[0040] Then, the horizontal relative position obtained by the horizontal position calculation unit 31 and the tsunami determination region S set in the previous position measurement cycle by the tsunami determination region setting unit 33 are input to the tsunami determination unit 32, where Then, it is determined whether or not the center position of the floating body 4 exists in the tsunami determination area S (step 2). In the initial tsunami determination period, a tsunami determination area that is set in advance is used.

[0041] When the floating body 4 exists in the tsunami determination area S, the floating body 4 has moved to an area beyond the range where the floating body 4 can move due to wind, ocean current, etc. The movement is judged to be caused by the tsunami.

[0042] Of course, if it is determined that the event is a tsunami, a notification to that effect is sent from the base station 2 to, for example, the Disaster Prevention Center (step 3).

[0043] On the other hand, when it is determined that it is not a tsunami (including when a tsunami is detected, in other words, after the tsunami detection processing is completed), the measurement position measured in the current position measurement cycle is the tsunami determination area setting unit. The tsunami detection area S for the next determination is set (step 4), and the above procedure is repeated to perform tsunami detection processing.

[0044] According to such a tsunami detection system, the positioning data detected by the GPS receivers 21 and 11 of the reference station 2 provided on land and the mobile station 5 provided on the floating body 4 on the sea surface are used. In addition, the real-time kinematic positioning method, which is relative positioning, accurately measures at least the amount of movement of the floating body 4 relative to the reference station 2 in the horizontal direction, and obtains the horizontal relative position of the moving force force floating body 4 to the mooring center position. And according to the horizontal relative position of the floating body 4 In addition to setting the tsunami judgment area S and determining whether the floating body 4 is in the tsunami judgment area S, for example, it is difficult to detect vertical displacement in deep sea areas Even so, the tsunami can be detected easily and accurately with only the amount of movement in the horizontal direction.

[0045] In addition, when setting the tsunami determination area S, it is determined by using an area setting coefficient (division ratio of line segments) based on experience or experiment. Therefore, the movement of the mooring center position C and the floating body 4 is determined. Since the limit circle A is divided in advance, it is easy to set the tsunami determination area S regardless of the position of the floating body 4 simply by obtaining the horizontal relative position (which is also the measurement position) of the floating body 4. And it can specify easily.

In the above embodiment, the tsunami determination period is described as being performed in accordance with the position measurement period of the floating body. However, the setting of the tsunami determination area S that does not need to be aligned with the position measurement period of the floating body is performed. Although it is performed at every measurement, it may be determined whether or not the force is a tsunami by using the tsunami determination area S set n times before every predetermined number of position measurements. In this way, by increasing the interval between the tsunami determination periods to some extent, it is possible to prevent erroneous recognition due to temporary disturbances such as gusts. Further, the position measurement cycle can be changed as appropriate. For example, if it is determined that the floating body is moving for each position measurement, the tsunami can be detected more quickly by shortening the tsunami determination cycle.

[0047] In the above-described embodiment, the tsunami determination region has been described by calculation based on the position of the floating body with respect to the mooring center position. However, for example, the direction in which the floating body is located (hereinafter referred to as a reference direction) It is also possible to obtain a tsunami determination area for this position according to the distance of the mooring center position force and use the tsunami determination area in this reference direction.

That is, the movement of the floating body is the same as the mooring center position regardless of the orientation of the floating body in view of the mooring center position force. For this reason, a reference azimuth is determined in advance, and a reference tsunami determination area is set according to the position of the floating body in this reference azimuth. By rotating the reference tsunami determination area around the mooring center position by the difference from the reference azimuth, the tsunami determination area can be set easily.

[0049] In the above embodiment, it is assumed that the tsunami detection device 6 is installed in the reference station 2. However, it should be a convenient location for system management regardless of where it is installed. For example, in this case, it may be installed in a land-based monitoring facility other than the reference station 2, and the positioning data obtained by the mobile-side GPS receiver 11 of the mobile station 5 and the reference-side GPS receiver 21 are used. The obtained positioning data is sent to the monitoring facility via the reference-side wireless device 22. Of course, the tsunami detection device 6 can also be installed on the mobile station 2 side.

[0050] In the above embodiment, the RT K method using GPS is used to determine the position of the floating body 4. However, a DGPS positioning method or a single positioning method, which is one of the relative positioning methods, is used. It can also be used, and it is possible to use other satellite positioning methods that are not limited to GPS.

[0051] Furthermore, in the above-described embodiment, the position of the floating body has been described as being obtained as a relative position with respect to the reference station. However, the positioning coordinate system by the satellite including the relative positioning method and the single positioning method described above is used. It can also be handled as the absolute position used.

Industrial applicability

[0052] According to the tsunami detection system of the present invention, the horizontal position of a floating body moored on the sea surface is accurately measured using a satellite, and can be moved by an external force such as normal wind or ocean current based on this measurement position. If the area between the judgment boundary line indicating the extension of a certain range and the movement limit circle of the floating body is set as the tsunami judgment area, and the floating body exists in this tsunami judgment area, it is judged as a tsunami. Therefore, the tsunami can be detected with high accuracy simply by measuring the current horizontal position of the floating body. In particular, it greatly contributes to the reduction of damage caused by tsunami caused by a large earthquake.

Claims

The scope of the claims

[1] A floating body moored on the sea surface by a mooring device, a position measuring device installed on this floating body that can receive radio waves from multiple satellites and detect its own position, and this position measuring device A tsunami detection system equipped with a tsunami detection device capable of detecting the presence or absence of a tsunami based on the obtained horizontal position data,

In the above tsunami detection device,

A tsunami detection area setting unit that inputs horizontal position data obtained by the position measuring device at predetermined time intervals and sets a tsunami determination area according to the current measurement position of the floating body relative to the mooring center position of the floating body, and this tsunami Tsunami detection system characterized by comprising a tsunami judging unit for judging the presence or absence of a tsunami based on whether or not the next measurement position of the floating body is included in the judgment region set in the judgment region setting unit .

[2] The tsunami judgment area is

A movement limit line indicating a movement limit of a predetermined radius around the mooring center position of the floating body, a plurality of lines connecting a plurality of straight lines extending from the center of the floating body and the above movement limit lines, and a plurality of lines connecting the floating body center And a decision boundary line obtained by connecting the division points divided by a predetermined ratio.

The tsunami detection system according to claim 1, wherein the tsunami detection system is a region in between.